The present invention relates to certain biscyclosiloxane imides such as 1,3-bis[5'-(heptamethylcyclotetrasiloxyl)-bicyclo[2.2.1]heptane-2',3'-dica rboxylicimido]phenylene. The conversion of the aforementioned biscyclosiloxane imide to more flexible resins by the use of an acid catalyst is also provided.
Prior to the present invention, biscyclosiloxanes, made by the hydrosilylation of vinyl-heptamethylcyclotetrasiloxane with 1,1,3,3-tetramethyldisiloxane, was shown by A. A. Zhdanov, V. M. Kotov et al., Izv. Akad. Nauk SSSR, Ser. Kim 1984. Bicyclosiloxanes to prepare networks has been reported by A. R. Gilbert et al., Journal of Polymer Science, 1959, 40,35. Ryang U.S. Pat. Nos. 4,381,396 and 4,472,565 assigned to the same assignee as the present invention and incorporated herein by reference, show the preparation of 5-(heptamethylcyclotetrasiloxyl)-bicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride and its use in making silicone-polyimide copolymers.
The present invention is based on the discovery, that a cyclosiloxane anhydride of the formula ##STR1## where R is a C.sub.(1-14) monovalent hydrocarbon radical or a C.sub.(1-14) monovalent hydrocarbon radical substituted with radicals inert during equilibration, and n is an integer having a value of 2 to 10 inclusive, can be made by the hydrosilylation of a bicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride with a mixture of cyclic siloxanes containing chemically combined diorganosiloxy units and organosiloxy units having hydrogen attached to silicon followed by fractional distillation to recover the desired cyclosiloxane anhydride. The cyclosiloxane anhydride of Formula (1) can thereafter be reacted with an organic diamine, such as metaphenylene diamine, to produce the desired biscyclosiloxane imide.